CN118605050A - Method for enhancing circularly polarized luminous signal and liquid crystal device - Google Patents

Abstract

The present invention discloses a method for enhancing circularly polarized luminescence signals and a liquid crystal device. The method comprises: regulating the molecular transition dipole of a non-chiral luminescent material so that the non-chiral material generates a significantly enhanced circularly polarized luminescence signal and optical activity without measurement angle directionality under a predetermined condition. The liquid crystal device comprises a plurality of liquid crystal boxes stacked vertically to each other, the plurality of liquid crystal boxes comprising a first liquid crystal box and a second liquid crystal box, the first liquid crystal box being adjacently arranged below the second liquid crystal box, the first liquid crystal box and the second liquid crystal box being filled with a first non-chiral liquid crystal material and a second non-chiral liquid crystal material, respectively, wherein the direction of the molecular transition dipole of the first non-chiral liquid crystal material is perpendicular to the direction of the molecular transition dipole of the second non-chiral liquid crystal material.

Description

Method for enhancing circularly polarized luminous signal and liquid crystal device

Technical Field

The present invention relates to a method and a liquid crystal device for enhancing circularly polarized light emitting signals, and in particular to a method and a liquid crystal device for enhancing circularly polarized light emitting signals by using non-chiral materials.

Background Art

Circularly polarized luminescent materials have a wide range of applications in optoelectronics, display, information storage and bio-labeling. They have attracted the attention of many researchers due to their optical activity, optoelectronic properties and other characteristics. However, the current development of circularly polarized luminescent materials mostly relies on the participation of chiral molecules, which are not only expensive but also difficult to separate, which greatly limits their promotion and use in practical applications.

Therefore, it is necessary to provide a method and a liquid crystal device for enhancing circularly polarized luminescence signals, which can use low-cost and easily available non-chiral materials to replace chiral materials to achieve circularly polarized luminescence and optical activity, so as to solve the problems existing in the prior art.

Summary of the invention

In view of this, the present invention provides a method and a liquid crystal device for enhancing circularly polarized light, which uses non-chiral materials to replace traditional chiral materials as circularly polarized luminescent materials, thereby reducing costs. At the same time, by simply adjusting the configuration of the non-chiral materials and the liquid crystal device, the circularly polarized luminescence and optical activity can be enhanced.

To achieve the above-mentioned purpose, one embodiment of the present invention provides a method for enhancing circularly polarized luminescence, which comprises the following steps: regulating the molecular transition dipole of a non-chiral luminescent material so that the non-chiral material produces an enhanced circularly polarized luminescence signal and optical activity under predetermined conditions, wherein the circularly polarized luminescence signal has no measurement angle directionality.

In one embodiment of the present invention, the predetermined conditions include: the non-chiral material has at least two sets of molecular transition dipoles, the at least two sets of molecular transition dipoles are respectively oriented in a first direction and a second direction, and the first direction and the second direction are perpendicular to each other; when the at least two sets of molecular transition dipoles are superimposed, the circularly polarized light luminescence signal is generated in the transition emission along a third direction.

In an embodiment of the present invention, the third direction is perpendicular to the first direction and the second direction respectively.

In one embodiment of the present invention, the achiral light-emitting material comprises light-emitting molecules with uniform and controllable orientation, and the uniformity of the transition dipole is ensured.

In one embodiment of the present invention, the method further comprises a step of observing the circularly polarized luminescence signal in a measuring direction, wherein the measuring direction is perpendicular to the molecular transition dipole moment of the achiral luminescent material.

Another embodiment of the present invention provides a liquid crystal device, wherein the liquid crystal device includes a plurality of liquid crystal boxes stacked vertically with each other, the plurality of liquid crystal boxes include a first liquid crystal box and a second liquid crystal box, the first liquid crystal box is adjacently arranged below the second liquid crystal box, the first liquid crystal box and the second liquid crystal box are respectively filled with a first achiral liquid crystal material and a second achiral liquid crystal material, wherein the direction of the molecular transition dipole of the first achiral liquid crystal material is perpendicular to the direction of the molecular transition dipole of the second achiral liquid crystal material.

In one embodiment of the present invention, the first achiral liquid crystal material and the second achiral liquid crystal material are the same or different.

In one embodiment of the present invention, the plurality of liquid crystal boxes further include a third liquid crystal box disposed above the second liquid crystal box, the third liquid crystal box being filled with a third non-chiral liquid crystal material, the direction of the molecular transition dipole of the third non-chiral liquid crystal material being the same as the direction of the molecular transition dipole of the first non-chiral liquid crystal material.

In one embodiment of the present invention, the third achiral liquid crystal material is the same as or different from the first achiral liquid crystal material; and the third achiral liquid crystal material is the same as or different from the second achiral liquid crystal material.

In one embodiment of the present invention, the first achiral liquid crystal material, the second achiral liquid crystal material and the third achiral liquid crystal material are all in liquid crystal phase.

Beneficial effects of the present invention:

By specifically processing and configuring the non-chiral material, the asymmetry factor of the circularly polarized luminescence of the non-chiral material can be greatly increased, and the sign of the asymmetry factor g _lum of the circularly polarized luminescence will flip as the number of stacking increases. This result shows that through simple stacking, the liquid crystal device of non-chiral material can achieve the circularly polarized luminescence and optical activity of chiral material, which has important application value for the preparation of liquid crystal displays, optoelectronic devices, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a distribution diagram of the asymmetry factor of the circularly polarized luminescence signal of the unamplified 5CB liquid crystal material in the angle-changing experiment, with an excitation wavelength of 310 nm.

Figure 2 is a distribution diagram of the asymmetry factor of the circularly polarized luminescence signal of the 5CB liquid crystal material in different bands after being stacked and amplified by different numbers of liquid crystal boxes in an angle changing experiment, with an excitation wavelength of 310nm.

FIG. 3 is a distribution diagram of the asymmetry factor of the circularly polarized luminescence signal of the unamplified 221 liquid crystal material in the angle-changing experiment, with an excitation wavelength of 320 nm.

FIG4 is a distribution diagram of the asymmetry factor of the circularly polarized luminescence signal of the 211 liquid crystal material amplified by stacking different numbers of liquid crystal boxes in an angle changing experiment in different wavelength bands, with an excitation wavelength of 320 nm.

DETAILED DESCRIPTION

In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the preferred embodiments of the present invention will be specifically cited below, and the accompanying drawings will be described in detail as follows. Furthermore, the singular forms "one", "an" and "said" mentioned in the present invention include plural references unless the context clearly stipulates otherwise. Numerical ranges (such as A of 10% to 11%) include upper and lower limits (i.e. 10%≦A≦11%) if there is no specific description; if the numerical range does not define the lower limit (such as B below 0.2%, or B below 0.2%), it means that the lower limit may be 0 (i.e. 0%≦B≦0.2%). The above terms are used to illustrate and understand the present invention, not to limit the present invention.

An embodiment of the present invention provides a method for enhancing a circularly polarized luminescence signal, which mainly comprises the steps of: regulating the molecular transition dipole of a non-chiral luminescent material so that the non-chiral material produces an enhanced circularly polarized luminescence signal and optical activity under a predetermined condition, wherein the circularly polarized luminescence signal has no measurement angle directionality.

In one embodiment, the predetermined condition includes: the achiral material has at least two sets of molecular transition dipoles, and the at least two sets of molecular transition dipoles are oriented in a first direction and a second direction, respectively. Preferably, the first direction and the second direction are perpendicular to each other, for example, they can be the x-axis and y-axis directions, respectively. Therefore, when the at least two sets of molecular transition dipoles are superimposed, the circularly polarized light emission signal is generated in the transition emission along a third direction. Preferably, the third direction is perpendicular to the first direction and the second direction, respectively, and can be, for example, the z-axis direction.

Preferably, the non-chiral light-emitting material comprises light-emitting molecules with uniform and controllable orientation, and can ensure the uniformity of transition dipoles. The non-chiral light-emitting material can be, for example, liquid crystal molecules 4-cyano-4'-pentylbiphenyl (referred to as liquid crystal molecules 5CB) or 4-butyl-2,6-difluoro-4'-(4-propylphenyl)-diphenylacetylene (CAS number: 221526-79-0, referred to as 221 liquid crystal molecules), or other nematic liquid crystal materials that can emit light.

In one embodiment of the present invention, the method further comprises a step of observing the circularly polarized luminescence signal in a measurement direction, wherein the measurement direction is perpendicular to the molecular transition dipole moment of the achiral luminescent material.

Another embodiment of the present invention provides a liquid crystal device. The liquid crystal device includes a plurality of liquid crystal boxes stacked on each other. The number of the plurality of liquid crystal boxes is not limited, and may be, for example, 1, 2, 3, 4, 5, 6, 7..., and may be set as required. The plurality of liquid crystal boxes include a first liquid crystal box and a second liquid crystal box. The first liquid crystal box is disposed adjacently below the second liquid crystal box, that is, stacked on each other. The first liquid crystal box and the second liquid crystal box are respectively filled with a first non-chiral liquid crystal material and a second non-chiral liquid crystal material. Preferably, the direction of the molecular transition dipole of the first non-chiral liquid crystal material is perpendicular to the direction of the molecular transition dipole of the second non-chiral liquid crystal material.

In one embodiment of the present invention, the first achiral liquid crystal material and the second achiral liquid crystal material may be the same or different.

In one embodiment, the plurality of liquid crystal boxes further include a third liquid crystal box, which is arranged above the second liquid crystal box and filled with a third non-chiral liquid crystal material. Preferably, the direction of the molecular transition dipole of the third non-chiral liquid crystal material is the same as the direction of the molecular transition dipole of the first non-chiral liquid crystal material. That is, the direction of the molecular transition dipole of the third non-chiral liquid crystal material is also perpendicular to the direction of the molecular transition dipole of the second non-chiral liquid crystal material. Preferably, the third non-chiral liquid crystal material and the first non-chiral liquid crystal can be the same or different, and the third non-chiral liquid crystal material and the second non-chiral liquid crystal material can be the same or different. Preferably, the first non-chiral liquid crystal material, the second non-chiral liquid crystal material and the third non-chiral liquid crystal material are all the same. In one embodiment, the first non-chiral liquid crystal material, the second non-chiral liquid crystal material and the third non-chiral liquid crystal material are all liquid crystal phases. The liquid crystal phase of the liquid crystal material can be obtained by, for example, heating the liquid crystal material under a constant temperature environment until it is transformed into an equiaxed phase, pouring the liquid crystal material into the liquid crystal box by a capillary method, and then cooling the liquid crystal box under a constant temperature environment.

The above predetermined conditions include that the non-chiral luminescent material must have at least two sets of transition dipoles, which can be oriented in the x and y directions, which are perpendicular to each other, respectively. When these transition dipoles are superimposed together, they will generate circularly polarized light in the transition emission along the z direction perpendicular to each other. This design condition is simple and can be achieved by simply stacking non-chiral luminescent materials, and the asymmetry factor is high, which is no less than the performance of chiral luminescent materials.

In addition, in order to achieve this special molecular transition dipole, the molecular orientation of the luminescent material needs to be highly uniform and controllable, and the uniformity of the transition dipole needs to be ensured.

In order to verify the performance of the method and liquid crystal device of the present invention in enhancing circularly polarized luminous signals, the following experiments were conducted.

Example 1: Preparation of Liquid Crystal Device Using Non-Chiral Liquid Crystal Material (Liquid Crystal Molecule 5CB)

Step 1: First, prepare the liquid crystal molecules 5CB and ECB liquid crystal box. Then, clean the liquid crystal box to ensure the accuracy of the experiment. The cleaning of the liquid crystal box can be achieved by ethanol and ultrasonic.

Step 2: Next, the clean ECB liquid crystal box is placed in a constant temperature environment to ensure its stability. Then, the 5CB liquid crystal molecules are heated in a constant temperature environment until they are transformed into an equiaxed phase.

Step 3: Slowly inject the preheated liquid crystal molecules into the liquid crystal box, and use the capillary phenomenon to evenly fill the liquid crystal box. After the liquid crystal molecules are filled, place the liquid crystal box in a constant temperature environment and slowly cool it down, so that the liquid crystal molecules change from the isometric phase to the liquid crystal phase.

Step 4: Mark one of the faces of the liquid crystal box prepared in step 3 with an upward arrow, prepare three to six liquid crystal boxes identical to those prepared in step 3 and mark them similarly, three to six fixing plates and enough tape. Place the first liquid crystal box on a flat surface with the arrow facing upward. Rotate the second liquid crystal box 90 degrees clockwise and place it on the first box so that the edges of the two boxes are aligned.

Step 5: Use fixing plates and tape to fix the first and second LCD boxes along the edges to ensure their position is stable.

Step 6: Repeat the above steps, stack the remaining LCD boxes on the previous box, rotate them 90 degrees, and then fix them with a fixing plate and tape.

Step 7: Make sure that three to six LCD boxes are all fixed together and the stacking structure is stable. Check whether all LCD boxes are correctly stacked together in the order of ↑→↑→↑ (and so on), and whether the angle between each two is 90 degrees.

Step 8: Finally, check again before conducting the experiment whether the stacked LCD cells are stable and whether all edges are properly fixed by fixing plates and tapes.

After the preparation was completed, the asymmetry factor was measured using a spectrophotometer (commercial instrument model CPL-300).

After completing the experiment, carefully dismantle the stacked structure and recycle or dispose of the liquid crystal box, fixing plate and tape separately.

Through the above embodiments, it is found that the circularly polarized luminescence properties and optical activity properties of the non-chiral liquid crystal box are in accordance with the combined experimental process. That is, when these non-chiral liquid crystal box units are operated according to the combined experimental process, it is found that the asymmetry factor of the non-chiral circularly polarized luminescence of the material is greatly increased, as shown in Figures 1 and 2. Among them, Figure 2 includes measurement data at different angles after five (5-405~420, 5-430~450, 5-405~420-1) and six liquid crystal boxes (6-430~450-1, 6-405~420-2, 6-430~450-2) are stacked.

As shown in FIG. 1 , the asymmetry factor fluctuates within the range of -0.02 to 0.01, and the value changes with the measurement angle. In FIG. 2 , after the combined device is formed, the asymmetry factor of the device is increased by more than 10 times.

This result shows that by simple stacking and fixing, the liquid crystal cell filled with achiral liquid crystal materials can achieve circularly polarized luminescence and optical activity of chiral materials.

Example 2: Preparation of a Liquid Crystal Device Using Non-Chiral Liquid Crystal Materials (Liquid Crystal Molecules 221)

Step 1: First, prepare the liquid crystal molecule 4-butyl-2,6-difluoro-4'-(4-propylphenyl)-diphenylacetylene (CAS No.: 221526-79-0, referred to as 221 liquid crystal molecule) and the ECB liquid crystal box. Then, clean the liquid crystal box to ensure the accuracy of the experiment. The cleaning of the liquid crystal box can be achieved by ethanol and ultrasonic.

Step 2: Next, the clean ECB liquid crystal box is placed in a constant temperature environment to ensure its stability. Then, the 221 liquid crystal molecules are heated in a constant temperature environment until they are transformed into an equiaxed phase.

Step 3: Slowly inject the preheated liquid crystal molecules into the liquid crystal box, and use the capillary phenomenon to evenly fill the liquid crystal box. After the liquid crystal molecules are filled, place the liquid crystal box in a constant temperature environment and slowly cool it down, so that the liquid crystal molecules change from the isometric phase to the liquid crystal phase.

Step 4: Mark one of the faces of the liquid crystal box prepared in step 3 with an upward arrow, prepare three to five liquid crystal boxes identical to those prepared in step 3 and mark them similarly, three to five fixing plates and enough tape. Place the first liquid crystal box on a flat surface with the arrow facing upward. Rotate the second liquid crystal box 90 degrees clockwise and place it on the first box so that the edges of the two boxes are aligned.

Step 5: Use fixing plates and tape to fix the first and second LCD boxes along the edges to ensure their position is stable.

Step 6: Repeat the above steps, stack the remaining LCD boxes on the previous box, rotate them 90 degrees, and then fix them with a fixing plate and tape.

Step 7: Make sure that three to five LCD boxes are all fixed together and the stacking structure is stable. Check whether all LCD boxes are correctly stacked together in the order of ↑→↑→↑ (and so on), and whether the angle between each two is 90 degrees.

Step 8: Finally, check again before conducting the experiment whether the stacked LCD cells are stable and whether all edges are properly fixed by fixing plates and tapes.

After the preparation was completed, the asymmetry factor was measured using a spectrophotometer (commercial instrument model CPL-300).

After completing the experiment, carefully dismantle the stacked structure and recycle or dispose of the liquid crystal box, fixing plate and tape separately.

Through the above embodiments, when the liquid crystal cell units of these non-chiral liquid crystal materials are operated according to the combined experimental process, it is found that the asymmetry factor of the circularly polarized luminescence of the non-chiral liquid crystal material increases significantly, as shown in Figures 3-4. Figure 4 includes measurement data at different angles after three (3-400-420, 3-430-450) and five (5-400-420, 5-430-450) liquid crystal cells are stacked.

As shown in FIG. 3 , the asymmetry factor fluctuates within the range of −0.01 to 0.04, and the value changes with the measurement angle. In FIG. 4 , after the combined device is formed, the asymmetry factor of the device is also increased by more than 10 times.

This result shows that by simply stacking and fixing, the liquid crystal cell filled with non-chiral liquid crystal materials can achieve circularly polarized luminescence and optical activity of chiral materials, which has important application value for the preparation of liquid crystal displays, optoelectronic devices, etc. The asymmetry factor is essentially a measure of the purity of circularly polarized light. The higher the polarization purity, the better the effect in practical applications (such as display, encryption, and optical communication).

The present invention relates to an application of a liquid crystal material, specifically, a method for realizing circularly polarized luminescence and optical activity of a chiral material under specific conditions by using a non-chiral liquid crystal material. The innovation of the present invention includes the discovery of a special design condition of a molecular transition dipole, which can enable a non-chiral material to realize circularly polarized luminescence and optical activity of a chiral material under this condition, and the use of a non-chiral liquid crystal material in a non-chiral liquid crystal box to realize a substantial increase in the asymmetry factor of the circularly polarized luminescence signal of the material under special conditions.

All the above research and findings have been verified under the corresponding experimental conditions, and have preliminarily achieved a substantial increase in the asymmetry factor of the circularly polarized luminescence signal of non-chiral liquid crystal materials in non-chiral liquid crystal boxes under special conditions. Improving the asymmetry factor of materials is of great significance for the development of new optical devices, 3D display technology, and asymmetric synthesis. This is not only expected to solve the problems of high cost and difficulty in separation of chiral molecules, but also to open up new paths for the research of circularly polarized luminescent materials.

The present invention has been described by the above-mentioned relevant embodiments, however, the above-mentioned embodiments are only examples for implementing the present invention. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, modifications and equivalent settings contained in the spirit and scope of the claims are all included in the scope of the present invention.

Claims (10)

1. A method for enhancing circularly polarized luminescence signals, characterized in that the method comprises the following steps: The molecular transition dipole of a non-chiral luminescent material is regulated so that the non-chiral material generates an enhanced circularly polarized luminescent signal and optical activity under a predetermined condition, wherein the circularly polarized luminescent signal has no measurement angle directionality. 2. The method for enhancing circularly polarized luminescence signals as described in claim 1 is characterized in that: the predetermined conditions include: the non-chiral material has at least two sets of molecular transition dipoles, the at least two sets of molecular transition dipoles are respectively oriented in a first direction and a second direction, and the first direction and the second direction are perpendicular to each other; when the at least two sets of molecular transition dipoles are superimposed, the circularly polarized light luminescence signal is generated in the transition emission along a third direction. 3. The method for enhancing circularly polarized luminous signals as described in claim 2, characterized in that the third direction is perpendicular to the first direction and the second direction respectively. 4. The method for enhancing circularly polarized luminescence signals as claimed in claim 1, characterized in that the non-chiral luminescent material comprises luminescent molecules with uniform and controllable orientation, and ensures the uniformity of transition dipoles. 5. The method for enhancing circularly polarized luminescence signals as described in claim 1, characterized in that: the method further comprises a step of observing the circularly polarized luminescence signal in a measurement direction, wherein the measurement direction is perpendicular to the molecular transition dipole moment of the non-chiral luminescent material. 6. A liquid crystal device, characterized in that: the liquid crystal device comprises a plurality of liquid crystal boxes stacked vertically to each other, the plurality of liquid crystal boxes comprise a first liquid crystal box and a second liquid crystal box, the first liquid crystal box is adjacently arranged below the second liquid crystal box, the first liquid crystal box and the second liquid crystal box are respectively filled with a first achiral liquid crystal material and a second achiral liquid crystal material, wherein the direction of the molecular transition dipole of the first achiral liquid crystal material is perpendicular to the direction of the molecular transition dipole of the second achiral liquid crystal material. 7 . The liquid crystal device according to claim 6 , wherein the first achiral liquid crystal material and the second achiral liquid crystal material are the same or different. 8. The liquid crystal device as described in claim 6 is characterized in that: the plurality of liquid crystal boxes further include a third liquid crystal box, which is arranged above the second liquid crystal box, and the third liquid crystal box is filled with a third achiral liquid crystal material, and the direction of the molecular transition dipole of the third achiral liquid crystal material is the same as the direction of the molecular transition dipole of the first achiral liquid crystal material. 9. The liquid crystal device of claim 8, wherein: the third achiral liquid crystal material is the same as or different from the first achiral liquid crystal material; and the third achiral liquid crystal material is the same as or different from the second achiral liquid crystal material. 10 . The liquid crystal device according to claim 9 , wherein the first achiral liquid crystal material, the second achiral liquid crystal material and the third achiral liquid crystal material are all in a liquid crystal phase.